The present invention relates generally to a brake device for a bicycle. More specifically, the present invention is directed to a cantilever brake device.
Different brake devices are adapted into different bicycles whether used for off-roading, touring, or a combination of both, to provide a stable and reliable braking device to accommodate the user's needs. Larger bicycles such as tandem, travel, or loaded touring bicycles, typically require stronger braking devices due to the added weight of a passenger, touring necessities, or a combination of both. Therefore, it is highly desirable to have a braking apparatus that is powerful, easily adjustable and highly reliable.
Mountain bicycles typically use what are called V-brakes® (also referred to as direct-pull cantilever brakes) and disc-brakes which are specifically designed for off-road use. V-brakes® are basically direct-pull cantilever brakes using a single cable with the arms extending straight upward. The cable housing connects to one arm while the inner cable runs across the top of the tire to the opposite arm to an anchor bolt. V-brakes® operate by pulling the brake cable from the side or applying the brake, thereby the housing pushes against on a cantilever arm while the inner cable pulls the other cantilever arm towards the rim surface of the tire. V-brakes® are a side-pull design rather than a center-pull design. Disc brakes basically utilize a metal disc that is attached to the wheel hub and rotates with the wheel for stopping the rotation of a wheel. A brake disc or calipers made of different materials are attached to the frame or fork with pads that squeeze together on the disc for stopping the wheel. Even though many mountain bicycles use and tandem bicycle manufacturers install V-brakes® or disc brakes, many of these brakes require frequent adjustment or complete replacement since these V-brakes® or disc brakes are not the most durable brakes, particularly for tandem bicycles and touring bicycles with added weight for touring or traveling.
The problem with V-brakes® is that they require special long-pull low tension levers rather than the standard short-pull high tension levers normally installed on bicycles, and are not compatible with any standard bicycle brake levers. V-brakes® are more acceptably used on mountain bicycles because users do not typically travel long distances. For touring and tandem bicycles, it is common for a user to ride more than 50 miles per day and travel long distances. Especially for an off-road situation, the weight of the rider and the bicycle can easily add up to 175 pounds, if not more. However, a touring bicycle with its rider and essentials for touring can easily weigh up to 250 pounds and well over 400 pounds on a loaded tandem bicycle. The typical conditions of off-roading include terrain of loose dirt and mud with the most high speed reached at around 25 miles per hour. V-brakes® have pads that are very thin, approximately 2 mm, which can wear out quickly for long distances. In comparison, cantilever brakes typically have brake pads that have at least twice as much thickness or 5-10 mm before the pads wear out. The V-brake pads have an approximate life time of 250 to 300 miles while the cantilever pads can last for thousands of miles before they are completely worn out. Therefore, it is highly desirable to have brakes that are less expensive, and last substantially longer than V-brakes® to accommodate heavier bicycles or bicycles with a heavier load over an extended period of travel.
Disc brakes are also problematic in that the discs and the calipers used to stop the disc increase the weight of the bicycle which is not preferred for touring or traveling bicycles. Furthermore, disc brakes stop the wheel of a bicycle at the hub which causes additional stress on the spokes, rim and frame at which point the wheel also attaches. In order to accommodate the heavier disc brakes, heavier chain and seat components are required, and a brace is additionally required to be installed to avoid the frame's tendency to break. All of these added components contribute to increased weight of the bicycle. Disc brakes are not as desirable for touring and tandem bicycles since they can hinder easy packing of the bicycles due to the bulky rotors. Disc brakes also create noise caused by the inevitable and slight warping of the disc and require frequent adjustment which is not a viable option for users touring and biking for a long distance. Therefore, it is highly desirable to have brakes without requiring the added bulk and weight of associated disc brake components, while providing brakes that are lighter, easier to adjust, less expensive, and last substantially longer than disc brakes to accommodate heavier bicycles or bicycles with a heavier load over an extended period of travel.
Traditional center-pull cantilever brakes were invented for touring and tandem bicycles decades before mountain bikes were created. Traditional cantilever brakes use two cables with a main cable running down the centerline of a bicycle, and the second transverse cable connecting the cantilever members on each side of the wheel. By applying the brakes or pulling the main line upwards, thereby pulling the middle of the transverse cable, the ends of the cantilever members, on which the transverse cables are anchored, cause inward pivotal movement of the brake shoes to touch the rim surface of the wheels. Because cantilever brakes typically have straight body members with an already fixed angle of the arms protruding outwardly from the body members at the top portion, also on which the transverse cables are attached to the top ends, the only way to accommodate wider frames such as tandem bicycles or other bicycle frames is to adjustably move the brake shoes closer to the rim surface. A problem remains in that the closer the brake shoes are to the rim surface and farther away from the shoe housing and the cantilever brake body members, the less stable are the brake pads to effectively stop the wheels. It is therefore desirable to have improved brakes that are easily adjustable without compromising the stability of braking power for any bicycles and bicycle frames with wider-spaced forks or frames.
A common problem exists to which there is no immediate solution whereby brakes create high squeaking noise caused by friction between the brake pads and the rim surface, thereby flexing the brake arms which are repeated at high speeds until the bicycle slows down or halts to a complete stop. This squealing problem is exacerbated when the brake shoes are moved closer to the rim surface due to wider frames and usual wear and tear associated with the brake pads. It is therefore highly desirable to have a brake design that avoids increased flexing of the brake shoes and squealing noise with sturdy, rigid support to stabilize the brake pads without having to move the brake shoes closer in to the rim surface. Because there is loss of braking power by moving the brake shoes in excessively without moving the other brake components with the brake shoes, the present invention is much more advantageous in design without requiring the brake shoes to be moved in excessively for adjustment.
Center-pull cantilever brakes are typically pulled at the arms, the top ends of the body units, while pivoting points are below the rim surface on the bottom ends of the body units which are normally attached to the fork section of the bicycle frame. While pulling the cable upwards and pivoting the cantilever body units with attached brake shoes for the inward braking action, the brake pads are primarily pulled upwards to the rim surface resulting in significant braking power. It is therefore highly desirable to design cantilever brakes to avoid losing significant braking power by utilizing different pulling, tension points to bring the brake pads evenly into contact with the rim surface.
Adjusting the toe of the brake pads for proper function by contact with the rim surface of the wheel is crucial for any brake. The brake shoe adjustment refers to different ways by which the brake shoes can be adjusted to work best for contacting the rim surface for the braking action. Adjusting the height of the brake shoes is critical because the brake shoes need to be perfectly aligned so that the brake pads touch the rim surface when engaged rather than the tire or the spokes. Adjusting the horizontal distance of the brake shoes to and from the rim surface with reasonable distance is also required for the brake pads to come into contact with the rim surface when the brakes are applied.
The roll angle typically refers to adjusting the brake shoes on a pivotal, vertical axis to touch and follow the slight curvature of the rim surface as closely as possible when the brakes are applied. The pitch angle typically refers to adjusting the brake shoes on a pivotal, horizontal axis to align the pads squarely against the rim surface so that the top and bottom portions of the brake pads touch the rim surface equally for maximum braking power when the brakes are applied.
The toe-in adjustment refers to the adjustment of the brake shoes and brake pads so that the front edge of the brake shoes contacts the rim surface slightly before the rear edge when the brakes are applied to decrease the squealing noise while increasing the braking power without affecting the other angles to avoid diminishing any braking function. These adjustments of the brake shoes for optimal performance is a very difficult task for any bike mechanic or adjuster to fine tune all of the adjustments and to secure the various adjustments without affecting other positions. The currently existing cantilever brakes do not have easily adjustable components for fine tuning all of the adjustments. A problem with the currently existing cantilever brakes is that the adjustments are predisposed to set into certain positions. The brake shoes currently used with existing cantilever brakes allow the adjustments to fall into pre-set notches or positions so that fine tuning of all of the different adjustments is not possible with current designs. Therefore, it is highly desirable to have a cantilever brake design with easy angle, height, and extension adjustments of the brake shoes and brake pads without setting into preset positions and readily securing the various adjustments for optimal performance, stability, rigidity, and increased braking power with reduced squealing noise.